Early May-late May, late July-late Sept. common migrant. common summer resident in north and rare summer resident (locally) in central *01*. In 1982 nests located in McHenry Co., Cook Co., Lake Co. *17*.

Comments on status:See *02* for present distribution. The black tern suffers from destruction of habitat and small population numbers *02*. This species is protected under the Illinois Endangered Species Act, 1972 *02*, the Migratory Bird Treaty Act, 1918 *16* and the Illinois Wildlife Code, 1971 *18*.

Comments on feed-guilding:Black terns apparently glean most insect prey off marsh vegetation or from the air *04,05,06*. Sometimes thought of as primarily insectivorous, but does take fish and a substantial amount is fed to chicks *10*.

Comments on food habits: General: Black terns eat mostly insects but also take small fishes. Odonates appear important.Juvenile: It appears fish make up a substantial proportion (up to 13%) of a chick's diet. Fish may provide at least 1/3 of the protein required by a growing chick *10*.Adult: See comments on general food habits.

Comments on environmental associations:General: No comments.Feeding juvenile: Upon fledging young birds establish feeding territories characterized by available perches, emergent vegetation, and open water. See *06*.Resting juvenile: Juveniles rest in nest, marsh vegetation, and on perches (floating logs, etc.) *04,06,09*.Feeding adult: Emergent vegetation (i.E. Cattails, bulrushes) are a primary source for insect prey. Insects and small fishes are taken from open water. Unpolluted wetland situations.Resting adult: ADULTS PREEN OR SLEEP LIGHTLY WHEN ON NEST *06*.Breeding adult: Wetland situations with interspersion of emergent vegetation and open water *07*. Plant species composition may vary but density is usually moderate *10*. Water level from 1 m-1 ft. deep and nests usually adjacent to open water *10*.

Reproduction: Breeding season from late May-late July *01,05*. Courtship is somewhat ritualized including posturing and aerial gliding similar to common tern, see *06*. Unclear who chooses territory but presumed male. Who chooses nest site unknown. Preferred nest site where vegetation low and thin as approaching areas of open water. For detailed description see *06,10*. Nest often placed on pre-existing mat of floating dead vegetation lodged in emergent vegetation *07,10*. Also, old flattened muskrat lodges *05*. Fairly opportunistic as long as low wet substrate. Female apparently constructs the nest using materials gathered from water surrounding nest, usually old weed stems, dead rushes, wet and decaying plant materials *05,09*. Construction varies from elaborate to mere depression in prostrate vegetation *05*. Eggs are olive or buff colored, heavily spotted with brown *04,05*; dimensions, mean = 34 x 24 mm.; wt. mean = 10 gm. (20) *10*. Ave. clutch size is 3 (2-5) *04,05,06,07,09,10*. Eggs are layed on 1 day intervals *06,10*. Both sexes incubate, 21-22 days *04,06,07*. Incubation begins after the 1st egg *10*. Hatchlings are precocial, covered in cinnamon down with black spots and white faces; wt. mean = 7.25 g (3) *10* (for descript. see *06,10). Both sexes brood, exhibiting nest-reinforcement behavior at change-over *06*. Chicks are able to leave nest at 2 days of age, and fledging occurs approximately 19 days *04,06,10*. Flight occurs at approximately 25-30 days *04,10*. (Chick development described in *06,10*). At this time, individual broods establish feeding territories, being attended by only 1 adult; at approximately 38 days can feed themselves *06*. In the southern part of breeding range, black terns may raise 2 broods per year *04*. Breeding age not available.

Behavior: Cuthbert (1954) considers black tern 'partially colonial' *06*, though group tenacity has been observed *10*. Loose colonies rarely exceed 20 prs. and scattered isolated nests often observed *06*. Territory size is unavailable see *05,06,09,10* for distance between nests. Black terns are very aggressive toward intruders *08, 04,06*. Chicks leave nest upon disturbance of parental signal and hide in surrounding vegetation *04,05,06,09*. A feeding territory is established and defended after fledging, see *06*. Black terns are primarily insectivorous but do forage for small fish with substantial amounts (up to 13%) being fed to young *10*. Diet and other parameters reduce competition between this species and marsh co-inhabitant Forster's tern (see *07*). The black tern shows flexibility concerning nest substrate but general habitat requirements are essential *07,10*. May build axillary nests *06*.

Limiting factors: Habitat *02,12*; wind and wave action *07*; water levels *12* enemies, assumed to be similar to those of Forster's tern *00,04,05*; massive spraying of marshes with insecticides (mainly DDT) for mosquito control *04*.

Population parameters: Little information is available. Black tern populations in the great lakes appear to remain stable from year to year as long as marsh habitats are protected *12*. High water levels have destroyed much of this habitat, therefore the populations may be expected to decline *12*. Mortality and survival rates and sex ratio unavailable. Majority of mortality occurs at the egg stage *10*. Bergman et al. (1970) Reported 29% nesting success (see *07*). Ave. lifespan unknown. Oldest bird 17 yrs. 2 mos. recovered in Europe *04*.

Comments on management practices:Maintainance of high water quality, protection of habitat from destruction or alteration, and avoidance of human disturbance should be primary means of protection in Illinois *02*. Public awareness must be increased as to the values of marshes *02*. The black tern is protected by the Illinois Endangered Species Act 1972 *02* and the Migratory Bird Treaty Act, 1918 *16*, and the Ill. Wildlife Code, 1971 *18*.